The view element_types contains the data type descriptors of the elements of arrays. When a table column, composite-type attribute, domain, function parameter, or function return value is defined to be of an array type, the respective information schema view only contains ARRAY in the column data_type. To obtain information on the element type of the array, you can join the respective view with this view. For example, to show the columns of a table with data types and array element types, if applicable, you could do:

This view only includes objects that the current user has access to, by way of being the owner or having some privilege.

Table 34-21. element_types Columns

Name

Data Type

Description

object_catalog

sql_identifier

Name of the database that contains the object that uses the array being described (always the current database)

object_schema

sql_identifier

Name of the schema that contains the object that uses the array being described

object_name

sql_identifier

Name of the object that uses the array being described

object_type

character_data

The type of the object that uses the array being described: one of TABLE (the array is used by a column of that table), USER-DEFINED TYPE (the array is used by an attribute of that composite type), DOMAIN (the array is used by that domain), ROUTINE (the array is used by a parameter or the return data type of that function).

collection_type_identifier

sql_identifier

The identifier of the data type descriptor of the array being described. Use this to join with the dtd_identifier columns of other information schema views.

data_type

character_data

Data type of the array elements, if it is a built-in type, else USER-DEFINED (in that case, the type is identified in udt_name and associated columns).

character_maximum_length

cardinal_number

Always null, since this information is not applied to array element data types in PostgreSQL

character_octet_length

cardinal_number

Always null, since this information is not applied to array element data types in PostgreSQL

character_set_catalog

sql_identifier

Applies to a feature not available in PostgreSQL

character_set_schema

sql_identifier

Applies to a feature not available in PostgreSQL

character_set_name

sql_identifier

Applies to a feature not available in PostgreSQL

collation_catalog

sql_identifier

Name of the database containing the collation of the element type (always the current database), null if default or the data type of the element is not collatable

collation_schema

sql_identifier

Name of the schema containing the collation of the element type, null if default or the data type of the element is not collatable

collation_name

sql_identifier

Name of the collation of the element type, null if default or the data type of the element is not collatable

numeric_precision

cardinal_number

Always null, since this information is not applied to array element data types in PostgreSQL

numeric_precision_radix

cardinal_number

Always null, since this information is not applied to array element data types in PostgreSQL

numeric_scale

cardinal_number

Always null, since this information is not applied to array element data types in PostgreSQL

datetime_precision

cardinal_number

Always null, since this information is not applied to array element data types in PostgreSQL

interval_type

character_data

Always null, since this information is not applied to array element data types in PostgreSQL

interval_precision

cardinal_number

Always null, since this information is not applied to array element data types in PostgreSQL

domain_default

character_data

Not yet implemented

udt_catalog

sql_identifier

Name of the database that the data type of the elements is defined in (always the current database)

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